I'll Prove It
by ThatFilmStudent
Summary: Sirius accidentally lets a truth slip but Remus doesn't believe him. So, Sirius tries to get Remus to believe him and offers a proposition to prove that he is serious. Remus/Sirius. Prequel is 'Those Three Words' but not essential to read it.


**DISCLAIMER: I do not own any of these HP characters or the song/lyric mentioned in the notes.**

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Grey eyes watched the smoke as their owner blew gliding clouds into the air slowly; he observed the swirls and odd patterns before the ghostly smoke dissipated and disappeared out of the ajar window into the dark atmosphere.

Sirius Black wasn't much of a smoker, not really. It was a bad habit and he didn't do it often enough for it to become an addiction. However, in more recent months, he'd been smoking a lot more. He usually only smoked (muggle) cigarettes when the occasion called for it. When he was drunk or if he was stressed. But, he smoked mostly after good things; like a good meal or a particularly spectacular shag.

A poorly hidden yawn sounded next to him and Sirius took a drag to hide the small affectionate smile that crept on his face. He blew out the smoke slowly as he offered the cigarette, without looking, to his bed-mate.

Remus looked at the cigarette and declined wordlessly, by not taking it. Sirius put it back to his own lips and took another smaller drag.

They lay against pillows that were propped against the headboard in silence. The bed sheets messy and only covering their bottom halves – except for Sirius' left leg which he had rested on top of the blanket. The silence was only punctuated by the outside noise from the streets below, and the city outside, and the two men's stuttered breathing as they slowly regained their wits they had lost from their previous activities.

"I should go," Remus said suddenly, but quietly enough not to startle Sirius. He flung the blanket off himself with a sort of elegance and stood up swiftly.

Sirius watched unabashedly as Remus searched for his clothes among the wreckage on the floor. He knew he should really get a washing basket but it wasn't a top priority at the moment. Or, he could clean his clothes straight away, but who had time for that?

"You don't want to stay the night?" Sirius asked casually before he drew in cigarette smoke.

Remus stopped for a moment before he picked up his shirt from the floor, having already found his boxer shorts and pulled them on. "Can't," he said, slowly turning to face Sirius. "I've got to go home. I haven't… let the cat out," he excused lamely.

Sirius frowned and blew out the smoke form side of mouth coolly. "You don't own a cat," he pointed out calmly.

Remus paused in buttoning his shirt up leaving it halfway done and plucked some black trousers from the ground. He pulled them on effortlessly as he spoke. "No," he agreed, looking up at Sirius. "But there's this one that always comes to the flat. And I feed it."

Remus returned his gaze to the floor as he looked for another item of clothing. Sirius stared at him, a small frown creasing his brow and butterflies – not the good kind – pommelling his stomach. Just as Remus picked up a belt, he spoke.

"You normally stay… Is this about what I said?" he asked calmly – sensing the real reason Remus was rushing to get away – though worry occupied his thoughts.

He hadn't meant to say it – to admit it; it just slipped out. And he certainly hadn't meant for what he said to effect Remus so much. Remus usually stayed on their nights. Sirius got the feeling he'd messed up. Remus only ever left if he really had to or if he was angry. Or sometimes when he couldn't sleep.

Remus paused on his belt before he looked up reluctantly with a tight smile. "It's okay, Sirius. What you said in the 'throes of passion' is void. I understand it was an accident. It's okay," he replied. "We'll just forget you said it," he shrugged lightly before he turned his attention back to the oh-so-intricate job of belting.

"Rem, I—"

Remus sighed and looked up again. "Sirius, really, it's fine." He knew what Sirius was thinking. Remus often tended to overthink things. It was a problem of his, and Sirius most likely thought that he was going to read too much into those words, and in the process end up breaking his own heart. "I'm not going to read into it. It was an accident. I know it was," he assured. "Let's just leave it at that."

Remus left no room for argument. He didn't really want to hear Sirius defend his untrue words. He already knew they weren't true; that they were said in the spur of the moment. That they held no true ground. The incident was best left unsaid and forgotten about, he decided.

He finished buckling his belt and searched the ground for his tie. He didn't often wear a suit and tie but they had been at a funeral earlier that day for one of the Order members, Diana Rosenfield. He had gone to Sirius's flat after after-funeral drinks.

He found it lying on the floor next to another – Sirius' – and moved over to pick it up. After a quick inspection, he determined his own and hung it around his neck. It was looser, but not undone completely as the other one was, since Sirius had hurried to rid it from him earlier. He tightened it slightly instead of doing it up again.

Sirius watched as he contemplated telling Remus the truth; that he had meant what he said. He hadn't been thinking properly when he said it but that didn't mean that it was any less true. It was a pure and truthful thought. It was the thought that was on his mind when they climaxed, he hadn't meant to blurt it out.

But he did mean it. Every single word. Admittedly there were only three of them, but still. Every word was true and each one held something of value, to him. But Remus didn't seem too keen to hear them again. Or to believe him, for that matter. Did he think Sirius was lying? Would it really be so bad that he meant it? Was it possible Remus didn't feel the same way?

He watched as Remus, even though he kept the tie loose, straightened out his collar over the top and made a little effort to tidy his appearance. It was one of his charms; his need to be politely presentable. It was what had drawn in Sirius at the beginning. If anyone else had been wearing oversized jumpers that made them look like muggle primary school teachers, he wouldn't have given them a second look. But Remus was different. And he had given a second look. And a third. And a fourth and so on. Remus made an effort on his appearance of out politeness rather than necessity; and Sirius loved that about him. Sirius loved a lot of things about him. Sirius just loved **him** , if he was to be honest. And he wanted to be; honest, that is. Remus, he decided, had to know.

"Rem, I meant it," he said quietly before he knew he'd done it. Remus froze as he stood in front of the small mirror on Sirius' wall and tried to sort his hair into a presentable state. He looked through the mirror to Sirius who was still sprawled elegantly and casually on the bed. Grey eyes locked onto hazel-amber through the mirror as he said the words again with a much clearer mind. "I love you," he said with conviction and a hint of challenge. "Remus, I love you."

Remus stayed frozen to the spot, staring into Sirius' eyes through the reflective surface, before he frowned and looked away. He took a deep breath and whirled around on the spot to stare at Sirius properly. Sirius looked defiant, challenging. His grey eyes clear and sincere and his posture slightly tense as if he was waiting for something. A fight, maybe? A confession?

Remus had no intentions to admit his own truths. He had no intentions to break his own heart and pin his hopes on a future with Sirius. Especially not when Sirius wouldn't be able to stick through with what he'd said. Sirius had only ever been in one relationship in his life and it had lasted no longer than six months. Sirius had admitted a couple of times to the Marauders that he didn't know what love was when he had asked in James and the Marauders in third and fifth year what it was. Remus had no intentions to return the words when he knew that Sirius probably didn't mean them. Even if he thought he did.

Sirius watched Remus, his stomach in knots when all Remus did was stare. Although, it didn't seem like he was staring. He seemed to be in some sort of haze. Sirius reckoned he had probably slipped into his thoughts again. He did that quite often; a side effect of being a dreamer and a genius.

"Say something," Sirius prompted, bringing Remus from his reverie.

Remus refocused his gaze on Sirius and noticed the almost-nervous disposition his best mate, and bed-buddy, had.

"No you don't," he finally said, a little sadly. "Sirius, you don't know what love is."

"I do," Sirius protested, sitting up in the bed and stubbing out the cigarette on the bedside table. He decided he'd fix the inevitable mark left there later. He turned his gaze back to Remus.

"How? How d'you know?" Remus challenged, watching Sirius intently.

Sirius didn't hesitate. "I know what love is. I might not have before, but I do now. It's you, Remus. It's not just a word. It's you and everything you do. It's everything you are… And I just know. I'm certain of it. I don't think I've ever been so sure of anything in my life." He paused as an earlier thought forced its way back to the forefront of his mind. "Do – do you not feel the same?"

Remus kept his mouth closed for a moment as he watched Sirius. Remus thought he looked vulnerable; he'd only seen that side a couple of times before. Sirius was never one for grand confessions – that was always James' department. Sirius tended to take a more subtle approach when it came to matters of emotion.

Sirius fidgeted under Remus' studying gaze and pulled the blanket tighter around his waist subconsciously, suddenly feeling very open and exposed. He kept his eyes on Remus but avoided the hazel-amber orbs for fear of not seeing what he truly wanted to see: a reciprocation of feelings. And instead seeing something he really didn't want to see: rejection.

"I'm not going to say it," Remus said eventually. "This," he gestured between them waving with one hand, "wouldn't work. So I'm not going to say it."

Sirius frowned. "So you do feel the same way?" Remus' silence answered him and he felt a small smile creep on his face before it was replaced with the frown again. "If you do, then why won't you give this a try?"

Remus sighed and moved to the bottom edge of the bed, still out of Sirius' reach but closer to him. "Sirius – you – if I say it, and later down the line you realise you were wrong, I don't know if I could handle it," he said honestly.

"I wouldn't **realise** anything," he said. "Why do you not believe me? I've never lied to you, Remus. Never. So, why d'you not believe me now? Is it so impossible that I'm in love with you?"

Remus moved his gaze down to his feet. He knew Sirius had never lied to him but that was beside the point. "Sirius, I don't want to wake up one day and for you to be gone." Sirius frowned and was about to ask what he meant when Remus continued. "You've spent your whole life running away," he said as he looked up. Hazel-amber met with grey again and Sirius could see the worry hidden in the depths. "Why would now be any different?"

Sirius' frown deepened as he tried to think of a reason that Remus would find viable. One that would convince the lycanthrope that he was in it for as long as Remus was. "It just is," he said finally. "I can't really explain it, Remus. It just is. You've changed me. I wouldn't have thought this possible. I wouldn't have thought I could fall in love, if it weren't for you." He paused, suddenly feeling the weight of his words. He just needed Remus to understand how much he meant to him. "You have made my life have meaning. I'm not going to give that up. I wouldn't run away from this. It's one of the only good things going on at the minute. Why would I ever run away from that?"

Remus growled, frustrated from the fact that Sirius seemed so adamant about it all. "Sirius, it… You might think you're in love with me, but what about when the war ends and you actually do fall in love? You'll leave me and I'll be stuck with my broken heart and only myself to blame for my own stupidity for even thinking this could happen."

Sirius drew out a breath as he stood up, making sure to keep covered since he still felt vulnerable and the feeling was only growing with Remus' continued rejection. He moved around the bed to stand in front of Remus. Up close and looking into those orbs, he could see how deep the worry went. It ran deep and Sirius just wanted to take it away. For him to be as sure as he was.

"Remus." He stared into Remus' eyes, urging him to see the truth and overwhelming love he felt that he couldn't actually put into words. "I can practically guarantee you that you're the only person I want to be with. Ever. This," he gestured between them even though neither of them were looking at his hand, " **You** , are what I want."

He took a step back to give Remus some room to think. "It's up to you now. Sometimes, you just need to take the risk. You need to trust that I wouldn't… You need to trust that I know how I'm feeling. If there's one thing I know, it's how I'm feeling. If you take this risk, you'll realise that I'm not going to leave. I want this. More than I'd care to admit. But, I'm leaving the choice up to you."

Remus searched Sirius' face. Genuine and defiant eyes stared back. Remus could see no trace of lie or insincerity. Only, what could be read as, love. Sirius looked, for once, serious. He looked as though he had so much trust in himself that he knew; he just knew that he was right and that he wouldn't leave. The amount of hope in his eyes made Remus' heart flutter and stomach plummet. What if Sirius actually did love him? Maybe he did know what love was. Remus knew what it was, after all. Why couldn't Sirius? What if Sirius didn't leave? What if Remus was enough to stop him from running?

But, then, what if, at the first sign of trouble, he did run away? Sirius always ran away from his problems, for as long as he could, until they caught up with him. What if his love for Remus was no different and when things got too serious, he ran away and abandoned him? Remus was in conflict with himself and as he looked at Sirius, he could feel his resolve crumble under the ardent, honest grey gaze.

Sirius could see it. He could see the battle behind Remus' eyes. The waging war that was pulling on his emotions. He could practically hear the cogs of possibilities turning in Remus' mind. He could almost see Remus weighing the pros and cons and he could see the negatives repeating in Remus' mind. The negatives making themselves known more than the positives. His face may have been a blank scape but his eyes could hide nothing from Sirius.

"I'll prove it to you," Sirius said suddenly bringing Remus' intense gaze back to him. "I'll prove to you that if you give this a try, I won't let you down. I'll prove that I do love you and that I won't leave you even when we're 50 years old." Remus' brow creased slightly as he let Sirius carry on. Sirius steeled himself for the fight to get Remus to say yes. "Move in with me, and I can prove it to you."

Remus' eyes widened a fraction as he stared at Sirius with nothing less than shock. "Uh – I… Um…" he stuttered.

Sirius quickly elaborated as he thought of the other reasons for Remus to move in with him. He'd been thinking about asking for a while and, for some reason, he decided that then would be the right time to ask.

"Really this makes sense," he began hastily when Remus said nothing. "To move in together, I mean. You spend a lot of nights here anyways and I'm used to your random bouts of cleaning and your sleeping pattern. And your flat costs so much anyways. If you did move in here, not only could I prove to you that I'm in this for as long as you'll have me, but also, it solves your rent problem… Remus, just take that leap of faith and I'll do everything in my power to prove to you that you were right to do so."

And with that final promise, Remus felt his resolve – all of the 'what ifs' – just disappear. Locked away in some box somewhere or gone altogether, he didn't know. What he did know was that he trusted Sirius and he believed him. With the look on Sirius' face, how could he not believe it?

He took a step forward and tentatively kissed Sirius. He pulled away just as quick as he'd pressed lips. "Okay," he said. "You prove me wrong."

Sirius grinned. "I intend to," he said before he leant up for another kiss.

Their lips met halfway and they kissed each other gently. Their lips slid together effortlessly and knowingly. It was a sweet and tender kiss. One usually reserved as a substitute for the words Sirius had said that night. However, it was simultaneously alike and unalike their other heartfelt kisses. While it was still one filled with love, this time they both knew it.

Sirius deepened the kiss as he cupped Remus' face with one hand and made sure to keep the other on the bedsheet around his hips. Remus accepted the kiss and returned it ardently without hesitation. He moved one hand to Sirius' shoulder and the other to his waist, pulling him closer.

They kissed for a short while but eventually the kiss came to a natural end. When Sirius pulled back to look up at Remus, he couldn't help the satisfied grin that appeared on his face.

"What?" Remus asked suspiciously, leaning back further to see the impish grin on Sirius' face clearly but not pulling out of the embrace.

Sirius shrugged and shook his head faintly. "Nothing. It's just… I have a new flatmate," he beamed. "And a… What do I call you?"

"Preferably Remus. Or Rem. Or Moony," Remus replied cheekily, earning him a gentle clap on the arm.

"Har har," Sirius drawled. "You know what I meant. Boyfriend's a bit… childish. Don't you think?"

"I don't think it is," Remus shrugged. His eyes fluttered closed for a second as Sirius's fingers tangled in the hair at the nape of his neck before he opened them again to stare back at Sirius. "But, I could see how you'd think that… I suppose it makes more sense to call me your partner," he mused. "Or maybe house-spouse."

"House-spouse?" he asked curiously, fingers still toying with the short hair.

"Prongs," he explained. "He coined it when he and Lily moved in together. Although, she was his fiancée by then so I don't know why he called her that."

Sirius chuckled. "Sound like something he learned from Wormtail," he said. "Didn't he used to say his mother had a bunch of 'House-Spouses' when he was young?"

"Yeah, he did," he agreed as he thought back. "I don't think he knew what it meant at the time. Partner it is then," he said decisively. Remus thought for a moment. "I'm Sirius Black's partner…" he tested aloud. "It doesn't sound as odd as I thought it would."

Sirius grinned. "I like the sound of that… 'Yes, I'm Sirius Black, partner of Remus J. Lupin'. That would be nice to say whenever I introduce myself," he mused. Remus snorted and nodded his agreement. "So… Do you want to stay tonight?" Sirius asked carefully.

Remus smiled and nodded. "Sure."

Sirius felt shocked for some reason. He had half expected Remus to say no. "Don't you have to go and let your cat out?" he recalled.

Remus' smile turned into a grin. "I let him out this morning."

Sirius narrowed his gaze. "You actually have a cat?" That shocked him more for some reason. "I thought that was just a shitty excuse to leave…"

Remus shrugged half-heartedly. "Well, it was. But, I do kind of have a cat too. I think he's the building's cat."

Sirius nodded slowly as he began to undress Remus again, tie first. "Okay… Well, he's not coming here. Padfoot would go mental."

Remus chuckled as Sirius began unbuttoning his shirt. "Probably," he agreed. "I had no plans to bring him anyway. All he does is eat the food. I spend loads on that little bastard," he muttered, more to himself than Sirius but the Animagus listened anyway.

Sirius slipped Remus' shirt off, leaving it in a crumpled heap on the floor with the rest of the clothes there, and pattered back over to the bed. He sat down on the bed and spread the blankets out for them as Remus took his trousers off himself. Sirius lay down and smiled to himself as he felt there was something strangely domestic about the scene. It made him feel even gladder that he'd told Remus the truth and asked him to move in. Remus slipped into the bed next to Sirius, pulling the blanket up to cover his chest and looked at Sirius expectantly.

"What?" Sirius asked innocently.

"The light," Remus said gesturing to the bedside lamp with his head.

"Oh," Sirius replied before he twisted over to turn it off.

The room was plunged into darkness and it took a couple of moments for them both to adjust to it. Sirius lay down properly, righting his pillows and he felt Remus doing the same. Once he was ready, he felt Remus' arm tentatively cross over him. He latched onto it, assuring Remus that it was definitely okay to 'have snuggles' as he'd once heard Mary call it when she complained Peter didn't do it often enough.

He pulled Remus' arm further around and thus pulling the body attached closer. He shuffled further back so that his back was flush against Remus' chest and he felt a sigh of contentment release as he settled into the embrace. Eventually, Remus' body became used to the position and he relaxed into it too. They lay in silence except from the outside world's noise and each other's calmed breathing.

"We'll move you in this week, if you want," Sirius suggested sleepily after a long while of silence. He wasn't sure if Remus was asleep or not.

"If you want," Remus murmured into Sirius' nape making Sirius' spine tingle and let out a – very **manly** , if you asked Sirius – giggle. Remus chuckled at the reaction which made Sirius giggle again.

"I do," he said squirming slightly.

Remus moved his face to a slightly different position to stop the reaction. "Okay," he mumbled.

They stayed in silence once more for no longer than a minute before Sirius broke it again. "I didn't mean to say it, you know," he admitted as he inspected the large hand he had clasped in his own. "I didn't mean for you to find out. But I don't regret it."

Remus smiled and lifted his head to give a small reassuring kiss to Sirius' shoulder. Only Sirius could evoke such feelings and make him want to bestow small loving kisses on him, he realised which made his smile grow. "I'm glad you told me," he replied.

"Me too…" Sirius turned over slightly press a quick chaste kiss on Remus' lips before he turned back. "I love you, Remus. And yes, I am going to be saying it quite a lot. Until you believe me," he informed as he settled into the embrace and pulled Remus' arm up further to use a sort of teddy/pillow.

Remus smiled. "I love you, too," he admitted quietly making Sirius grin from ear to ear. "Na night," he said.

"'Night," Sirius replied, unable to keep the happiness out of his voice from Remus' returned words.

If someone had told either of them that that was how their day would end, neither of them would have believed it. But, as they drifted off into a restful and peaceful slumber, they were glad it had ended that way.

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 **A/N: Thanks for reading! This story was much longer than I had originally anticipated and was inspired by the lyric:** **Oh, Angela, spent your whole life running.**

 **Inspired by: Angela by The Lumineers**

 **Written: October, 2016**


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